This invention relates to document projectors and more particularly to digital electronic projectors.
Today many business presentations requiring visuals are made using digital projection technology. While digital projectors are very costly, the quality is reasonably good and the convenience of being able to directly present slides prepared on a computer is attractive. However, many institutions such as schools or smaller businesses cannot justify the expense of such a device because of its limited capability and flexibility (only digital data files can be projected), and rely instead on overhead transparencies to make presentations. Overhead transparency projectors are relatively inexpensive but unless they are cleaned regularly and well maintained the image quality is often not very good and the preparation of transparencies, especially those in color made from computer files, is time consuming and quite costly itself in both time and materials.
There are further limitations to these two main presentation technologies. Digital projectors are limited in that they can only project a slide existing as a digital data file, normally residing on a personal computer hard drive, and overhead projectors can only project transparencies. Also, there are often last-minute additions which must be made to presentations, e.g. updated sales reports, recently published documents or advertising material, etc., and there may not be sufficient time to either convert the material to digital data files for projection by a digital projector or to a transparency for use with an overhead projector. It would be useful therefore to have a projector which is more flexible in the type of materials which could be projected.
One potential solution which addresses some of these limitations has been disclosed in Japanese laid-open patent application JP 09-294,236. The ""236 application discloses an apparatus which combines a document camera mounted in xe2x80x9ccopy standxe2x80x9d fashion on top of a digital projector. This device can capture a digital image of any object or document within the field of view of the camera and then subsequently project this digital image using the projector functionality. A significant limitation of this device, however, is the need to provide extra illumination for the camera. When such a projector is used in a darkened room, as is typical with digital projectors, the stray light from this illumination can detract from the quality of viewing. The overall image quality available from such a device is also impacted by the level and uniformity of this illumination, as well as by the resolution of the camera. The device is also typical of digital projectors in that it has no memory for the storage of multiple images.
These and other limitations of the prior art are addressed by the present invention.
The need is met according to the present invention by providing a document projector that includes a feed through scanner having a document transport, an illumination source, and a linear image sensor for scanning and producing a digital color image of a document or transparency; a microprocessor connected to the scanner for processing the digital image and for overall control of the apparatus; a memory connected to the microprocessor for storing the digital document image; and a digital projector connected to the microprocessor for projecting the digital image.
The document projector of the present invention has the advantage that a high quality display can be easily produced from either transparent or opaque originals. Previously displayed images are immediately available electronically without the need to reposition the originals, and extra slides can be easily inserted into a presentation during the presentation.